<TABLE>
<S>                               <C>                                  <C>
                                            84641648
 
APPLICANT'S ACC'T NO.                       841529                     Filed this 17th day of
                                    -----------------------            October, 1984           
DSCB:BCL--204 (REV. 8-72)            (Line for numbering)              Commonwealth of Pennsylvania
                                                                       Department of State
FILING FEE: $75
AIB-7                                                                  /s/ William R. Davis
 
Articles of                       COMMONWEALTH OF PENNSYLVANIA         Secretary of the Commowealth 
Incorporation--                        DEPARTMENT OF STATE               
Domestic Business Corporation          CORPORATION BUREAU  
- ------------------------------------------------------------------------------------------------------
                                                                          (Box for Certification)
</TABLE>
 
 
  In compliance with the requirements of section 204 of the Business Corporation
Law, act of May 5, 1933 (P. L. 364) (15 P. S. (S)1204) the undersigned, desiring
to be incorporated as a business corporation, hereby certifies (certify) that:
 
1.  The name of the corporation is:
 
    North Pittsburgh Systems, Inc.
- --------------------------------------------------------------------------------
 
2.  The location and post office address of the initial registered office of the
    corporation in this Commonwealth is:
    
    4008 Gibsonia Road
- --------------------------------------------------------------------------------
      (NUMBER)                                 (STREET)
 
    Gibsonia                    Pennsylvania                  15044      (02) 
- --------------------------------------------------------------------------------
    (CITY)                                                 (ZIP CODE)
 
3.  The corporation is incorporated under the Business Corporation Law of the
    Commonwealth of Pennsylvania for the following purpose or purposes:
 
      To own telecommunication systems and provide other services and equipment
      which are related to telecommunication services or which can be provided
      in conjunction with telecommunication activities.
 
      To acquire, purchase, sell, trade, hypothecate, pledge, deal in and hold
      its own securities and securities of other corporations and to deal in
      real and personal property or any interest therein;
 
      The Corporation which is incorporated under the provisions of the Business
      Corporation Law shall have unlimited power to engage in and to do any
      lawful act concerning any and all lawful business for which corporations
      may be incorporated under the provisions of the Business Corporation Law.
 
4.  The term for which the corporation is to exist is:   Perpetually
                                                       -------------------------
 
5.  The aggregate number of shares which the corporation shall have authority to
    issue is:
 
    1,000,000 shares of Common Stock, par value $3.125 per share 3,125,000.
<PAGE>
 
                                                                    PAGE 2 OF 16
                                                                        84641649
DSCB:BCL--204 (Rev. 8-72)-2
 
6.  The name(s) and post office address(es) of each incorporator(s) and the
number and class of shares subscribed by such incorporator(s) is (are):
 
<TABLE>
<CAPTION>
  NAME                                 ADDRESS                          NUMBER AND CLASS OF SHARES
                         (including street and number if any)
<S>                   <C>                                               <C>
Frank D. Reese        4008 Gibsonia Road, Gibsonia, PA 15044                    1 share Common
- ------------------------------------------------------------------------------------------------
Gerald A. Gorman      4008 Gibsonia Road, Gibsonia, PA 15044                    1 share Common
- ------------------------------------------------------------------------------------------------
Allen P. Kimble       4008 Gibsonia Road, Gibsonia, PA 15044                    1 share Common
- ------------------------------------------------------------------------------------------------
</TABLE>
 
7.  The Board of Directors, by a majority vote of its members, shall have the
    power to make, alter, amend, and repeal the by-laws of the corporation not
    inconsistent with its Articles or with law, subject always to the power of
    the shareholders to change such action.
 
8.  No holder of any Common Stock of the Corporation shall be entitled of right
    to subscribe for, purchase, or receive any proportionate share of any Common
    Stock to be issued and the Board of Directors may dispose of all or any
    portion of such stock if and when it may determine, whether by offering the
    same to stockholders or by sale or other disposition as the Board may deem
    advisable.
 
  IN TESTIMONY WHEREOF, the incorporator(s) has (have) signed and sealed these
Articles of Incorporation this 16th day of October, 1984.
 
/s/ Frank D. Reese        (SEAL)      /s/ Gerald A. Gorman             (SEAL)
- --------------------------            ---------------------------------
 
                                      /s/ Allen P. Kimble              (SEAL)
                                      ---------------------------------
 
 
INSTRUCTIONS FOR COMPLETION OF FORM:
 
  A.  For general instructions relating to the incorporation of business
      corporations see 19 Pa. Code Ch. 35 (relating to business corporations
      generally). These instructions relate to such matters as corporate name,
      stated purposes, term of existence, authorized share structure and related
      authority of the board of directors, inclusion of names of first directors
      in the Articles of Incorporation, optional provisions on cumulative voting
      for election of directors, etc.
 
  B.  One or more corporations or natural persons of full age may incorporate a
      business corporation.
 
  C.  Optional provisions required or authorized by law may be added as
      Paragraphs 7, 8, 9...etc.
 
  D.  The following shall accompany this form:
 
      (1) Three copies of Form DSCB:BCL--206 (Registry Statement Domestic or
          Foreign Business  Corporation).
 
      (2) Any necessary copies of Form DSCB:17.2 (Consent to Appropriation of
          Name) or Form DSCB:17.3 (Consent to Use of Similar Name).
 
      (3)  Any necessary governmental approvals.
 
  E.  BCL (S)205 (15 Pa. S. (S)1205) requires that the incorporators shall
      advertise their intention to file or the corporation shall advertise the
      filing of articles of incorporation. Proofs of publication of such
      advertising should not be delivered to the Department, but should be filed
      with the minutes of the corporation.
 
                                DEP'T OF STATE
                              OCT 17 4:00 PM '84
 
<PAGE>
 
                                                                   PAGE 3 OF 16
 
                                                                 
<TABLE>
<S>                               <C>                                  <C>
                                            
 
APPLICANT'S ACC'T NO._______                86722018                   Filed this 9th day of
                                    -----------------------            December, A.D. 1986
DSCB:BCL-806 (REV. 8-72)                     841529                    Commonwealth of Pennsylvania
                                                                       Department of State
FILING FEE: $40
AB-2                                                                   /s/ Robert A. Gleason, Jr.
 
Articles of                       COMMONWEALTH OF PENNSYLVANIA         Secretary of the Commowealth 
Amendment--                           DEPARTMENT OF STATE               
Domestic Business Corporation          CORPORATION BUREAU  
- ------------------------------------------------------------------------------------------------------
                                                                              DEC 09 1986
</TABLE>
  In compliance with the requirements of section 806 of  the Business
Corporation  Law, act of May 5, 1933 (P. L. 364) (15 P. S. (S)1806), the
undersigned corporation, desiring to amend its Articles, does hereby certify
that:
 
 
1. The name of the corporation is:
   
   North Pittsburgh Systems, Inc.
- -------------------------------------------------------------------------------
 
2. The location of its registered office in this Commonwealth is (the Department
   of State is hereby authorized to correct the following statement to conform
   to the records of the Department):
 
   4008 Gibsonia Road
- -------------------------------------------------------------------------------
       (NUMBER)                              (STREET)
 
   Gibsonia                    Pennsylvania                        15044
- -------------------------------------------------------------------------------
       (CITY)                                                    (ZIP CODE)
 
3. The statute by or under which it was incorporated is:
 
   Business Corporation Law, Act of May 5, 1933 (P.L. 364) as amended
- -------------------------------------------------------------------------------
 
4. The date of its incorporation is:  October 17,1984
                                    -------------------------------------------
 
5. (Check, and if appropriate, complete one of the following):
 
  [X] The meeting of the shareholders of the corporation at which the amendment
was adopted was held at the time and place and pursuant to the kind and period
of notice herein stated:
 
  Time:  The    5th        day of        December          , 1986.
             -------------        -------------------------    -- 
 
  Place: 4008 Gibsonia Road, Gibsonia, Pennsylvania
        ----------------------------------------------------------------------
 
  Kind and period of notice Written notice more than ten days before the
                           ---------------------------------------------
meeting, to each shareholder entitled to vote thereon setting forth the proposed
- --------------------------------------------------------------------------------
amendments in full.
- -------------------
 
  [ ] The amendment was adopted by a consent in writing, setting forth the
action so taken, signed by all of the shareholders entitled to vote thereon and
filed with the Secretary of the corporation.
 
6.  At the time of the action of shareholders:
 
   (a) The total number of shares outstanding was:
 
                               752,000
- -------------------------------------------------------------------------------
   (b) The number of shares entitled to vote was:
 
                               752,000
- -------------------------------------------------------------------------------
<PAGE>
 
                                                                    PAGE 4 OF 16
                                                                        86722019
DSCB:BCL--806 (Rev. 8-72)-2
 
 
7.  In the action taken by the shareholders: See attachment
 
- --------------------------------------------------------------------------------
 
 
- --------------------------------------------------------------------------------
 
8.  The amendment adopted by the shareholders, set forth in full, is as follows:
 
     See Attachment
 
 
 
  IN TESTIMONY WHEREOF, the undersigned corporation has caused these Articles of
Amendment to be signed by a duly authorized officer and its corporate seal, duly
attested by another such officer, to be hereunto affixed this   5th   day of
                                                              -------        
December , 1986.
- ---------    -- 
                                             North Pittsburgh Systems, Inc.
                                        ----------------------------------------
                                                  (NAME OF CORPORATION)
 
Attest:                             By             /s/ F. D. Reese
                                        ----------------------------------------
  /s/    G. A. Gorman                                 (SIGNATURE)
- ----------------------------------
           (SIGNATURE)                                 President
                                        ----------------------------------------
                                        (TITLE: PRESIDENT, VICE PRESIDENT, ETC.)
            Secretary
- ----------------------------------
(TITLE: SECRETARY, ASSISTANT
 SECRETARY, ETC.)
 
 
(CORPORATE SEAL)
 
INSTRUCTIONS FOR COMPLETION OF FORM:
 
  A. Any necessary copies of Form DSCB:17.2 (Consent to Appropriation of Name)
     or Form DSCB:17.3 (Consent to Use of Similar Name) shall accompany Articles
     of Amendment effecting a change of name.
 
  B. Any necessary governmental approvals shall accompany this form.
 
  C. Where action is taken by partial written consent pursuant to the Articles,
     the second alternate of Paragraph 5 should be modified accordingly.
 
  D. If the shares of any class were entitled to vote as a class, the number of
     shares of each class so entitled and the number of shares of all other
     classes entitled to vote should be set forth in Paragraph 6(b).
 
  E. If the shares of any class were entitled to vote as a class, the number of
     shares of such class and the number of shares of all other classes voted
     for and against such amendment respectively should be set forth in
     Paragraphs 7(a) and 7(b).
 
  F. BCL (S)807 (15 P. S. (S)1807) requires that the corporation shall advertise
     its intention to file or the filing of Articles of Amendment. Proofs of
     publication of such advertising should not be delivered to the Department,
     but should be filed with the minutes of the corporation.
 
                                DEP'T OF STATE
                               DEC 9 2:41 PM '86
 
<PAGE>
 
                                                                    PAGE 5 OF 16
                                                                        86722020
 
                         North Pittsburgh Systems, Inc.
 
                             Articles of Amendment
 
                           Attachment in Response to
 
                                Paragraph No. 7
 
 
 
Separate votes were taken on Amendments to the Articles of Incorporation
relating to Articles 5, 9 and 10. The following is the vote as to each
amendment.
 
       (a) The number of shares voted in favor of the amendment to Article 5
       was: 675,510.
 
       (b)  The number of shares voted against the   amendment to
       Article 5 was: 8,596.
 
       (c) The number of shares voted in favor of the amendment adding Article 9
       was: 597,449.
 
       (d) The number of shares voted against the amendment adding
       Article 9 was: 83,313.
 
       (e) The number of shares voted in favor of the amendment adding Article
       10 was: 601,121.
 
       (f) The number of shares voted against the amendment adding Article 10
       was: 77,955.
 
                                DEP'T OF STATE
                               DEC 9 2:41 PM '86
 
 
<PAGE>
 
                                                                    PAGE 6 OF 16
                                                                        86722021
 
                         North Pittsburgh Systems, Inc.
 
                             Articles of Amendment
                           Attachment in Response to
                                Paragraph No. 8
 
   Article 5 of the Company's Articles of Incorporation is restated and
amended to read in its entirety as follows:
 
   "5. The aggregate number of shares which the corporation shall be authorized
to issue is: 10,000,000 shares of Common Stock, par value $.625 per share,
aggregate par value $6,250,000."
 
   A new Article, Article 9 is added to the Articles of Incorporation of
the Company to read in its entirely as follows:
 
   "9.  The holders of shares of stock entitled to vote in the election of
Directors of the corporation shall not be entitled to cumulate votes for
the purpose of such election."
 
   A new Article, Article 10 is added to the Articles of Incorporation of
the Company to read in its entirely as follows:
 
   "10. In addition to any affirmative vote required by law or these Articles,
the affirmative vote of the holders of a majority of the outstanding shares of
"Voting Stock" (as hereinafter defined) held by shareholders other than "Related
Persons" (as hereinafter defined) shall be required for the approval or
 
                                DEP'T OF STATE
                               DEC 9 2:41 PM '86
<PAGE>
 
                                                                    PAGE 7 OF 16
                                                                        86722022
 
 
authorization of any "Business Combination" (as hereinafter defined) or of any
series of transactions which, if taken together, would constitute a Business
Combination of the corporation or any subsidiary with any Related Person;
provided, however, that a majority vote of shareholders other than Related
Persons shall not be required if:
 
    (1) The "Continuing Directors" of the corporation (as hereinafter defined)
by a majority vote (a) have expressly approved in advance the acquisition of
Voting Stock of the corporation that caused the Related Person to become a
Related Person, or (b) have approved the Business Combination; or
 
    (2) The Business Combination is a merger or consolidation and the cash
or fair market value of the property, securities or other consideration to be
received per share by holders of Common Stock of the corporation in the Business
Combination is not less than the highest per share price (with appropriate
adjustments for recapitalizations and for stock splits, stock dividends and like
distributions) paid by the Related Person in acquiring any of its holdings of
the corporations's Common Stock either in or subsequent to the transaction or
series of transactions in which the Related Person became a Related Person.
 
    Such affirmative vote shall be required notwithstanding the fact that no
vote may be required, or that a lesser percentage may be specified, by law or in
any applicable agreement with any national securities exchange or otherwise.
<PAGE>
 
                                                                    PAGE 8 OF 16
                                                                        86722023
 
                                                                               
    For the purpose of this Article 10:
    
    (a) The term "Business Combination" shall mean (i) any merger or
consolidation of the corporation or a subsidiary with or into a Related Person,
(ii) any sale, lease, exchange, transfer or other disposition, including without
limitation a mortgage or any other security device, of all or any "Substantial
Part" (as hereinafter defined) of the assets either of the corporation
(including without limitation any voting securities of a subsidiary) or of a
subsidiary, to a Related Person, (iii) any merger or consolidation of a Related
Person with or into the corporation or a subsidiary of the corporation, (iv) any
sale, lease, exchange, transfer or other disposition, including without
limitation a mortgage or other security device, of all or any Substantial Part
of the assets of a Related Person to the corporation or a subsidiary of the
corporation, (v) the issuance or transfer of any securities of the corporation
or a subsidiary of the corporation to a Related Person other than the issuance
on a pro rata basis to all holders of shares of the same class pursuant to a
stock split or stock dividend, or a distribution of warrants or rights, (vi) any
reclassification of securities (including a reverse stock split) or
recapitalization that would have the effect of increasing the voting power of a
Related Person, (vii) the adoption of any plan or proposal for the liquidation
or dissolution of the corporation proposed by or on behalf of any Related
Person, and (viii) any agreement, contract or other arrangement providing for
any of the transactions described in this definition of Business Combination.
<PAGE>
 
                                                                    PAGE 9 OF 16
                                                                        86722024
 
 
    (b) The term "Related Person" shall mean and include any individual,
corporation, partnership or other person or entity, other than any trustee or
fiduciary when acting in such capacity with respect to any employee benefit plan
or trust of the corporation or any of its wholly-owned subsidiaries, which,
together with its "Affiliates" and "Associates" (as defined on March 27, 1985 in
Rule 12b-2 under the Securities Exchange Act of 1934), "Beneficially Owns" (as
defined on March 27, 1985 in Rules 13d-3 and 13d-5 under the Securities Exchange
Act of 1934) in the aggregate 10 percent or more of the outstanding Voting Stock
of the corporation, any Affiliate or Associate of any such individual,
corporation, partnership or other person or entity, and any assignee of any of
the foregoing. For purposes of determining shareholders whose votes shall be
excluded pursuant to the first paragraph of this Article 10, the term (Related
Person) (i) shall include any shareholder acting jointly or in concert with a
Related Person in connection with a Business Combination and any shareholder who
will be treated differently than other shareholders in any Business Combination
(other than a shareholder who is entitled to the rights of a dissenting
shareholder under applicable law), (ii) but shall exclude a Related Person who
(x) is not the Related Person who is a party to the Business Combination being
voted upon, and (y) is not a shareholder described in clause (i) of this
sentence.
 
    (c) The term "Substantial Part" shall mean more than 30 percent of the
fair market value as determined by a majority of 
 
                                DEP'T OF STATE
                               DEC 9 2:41 PM '86
<PAGE>
 
                                                                   PAGE 10 OF 16
                                                                        86722025
 
 
the Continuing Directors of the total consolidated assets of the corporation in
question and its subsidiaries taken as a whole, as of the end of its most recent
fiscal year ending prior to the time the determination is being made.
 
    (d) Without limitation, any shares of Voting Stock of the corporation that
any Related Person has the right to acquire pursuant to any agreement, or upon
exercise of conversion rights, warrants or options, or otherwise, shall be
deemed beneficially owned by the Related Person.
 
    (e) For the purposes of section (2) of this Article 10, the term "other
consideration to be received" shall include, without limitation, Common Stock of
the corporation retained by its existing public shareholders in the event of a
Business Combination in which the corporation is the surviving corporation.
 
    (f) The term "Voting Stock" shall mean all outstanding shares of capital
stock of the corporation or another corporation entitled to vote generally in
the election of directors and each reference to a proportion of shares of Voting
Stock shall refer to such proportion of the votes entitled to be cast by such
shares.
 
    (g) The term "Continuing Director" shall mean a director who either (i) was
a member of the Board of Directors of the
<PAGE>
 
                                                                   PAGE 11 OF 16
                                                                        86722026
 
 
 
corporation immediately prior to the time that the Related Person involved in a
Business Combination became a Related Person or (ii) was designated (before his
or her initial election as director) as a Continuing Director by a majority of
the then Continuing Directors.
 
    Notwithstanding any other provision in these Articles, this Article 10 may
not be repealed or amended in any respect, and no provision inconsistent with
this Article 10 may be adopted, unless such action is approved by the
affirmative vote of the holders of a majority of the outstanding shares of
Voting Stock held by shareholders other than Related Persons."
 
                                DEP'T OF STATE
                               DEC 9 2:41 PM '86
<PAGE>
 
                                                                   PAGE 12 OF 16
 
 
Microfilm Number 9281-799     Filed with the Department of State on OCT 23 1992
                ----------                                          -----------
 
Entity Number     841529           /s/ Brenda K. Mitchell
              ------------    --------------------------------------------------
                                        Secretary of the Commonwealth
 
              ARTICLES OF AMENDMENT-DOMESTIC BUSINESS CORPORATION
                             DSCB:15-1915 (Rev 89)
 
 
    In compliance with the requirements of 15 Pa.C.S. (S)1915 (relating to
articles of amendment), the undersigned business corporation, desiring to amend
its Articles, hereby states that:
 
1. The name of the corporation is:    North Pittsburgh Systems, Inc.
                                     ------------------------------------------
 
- --------------------------------------------------------------------------------
 
2. The (a) address of this corporation's current registered office in this
   Commonwealth or (b) name of its commercial registered office provider and the
   county of venue is (the Department is hereby authorized to correct the
   following information to conform to the records of the Department):
 
 (a)    4008 Gibsonia Road       Gibsonia        PA      15044    Allegheny
    ---------------------------------------------------------------------------
    Number and Street            City          State      Zip      County
 
 (b)c/o:-----------------------------------------------------------------------
         Name of Commercial Registered Office Provider             County
 
For a corporation represented by a commercial registered office provider, the
county in (b) shall be deemed the county in which the
corporation is located for venue and official publication purposes.
 
3. The statute by or under which it was incorporated is: Business Corporation
                                                         --------------------
   Law, Act of May 5, 1933 (P.L. 364) as amended
   --------------------------------------------------------------------------
             
 
4. The original date of its incorporation is:           October 17, 1984
                                             ---------------------------------
 
5. (Check, and if appropriate complete, one of the following):
   
   -----  The amendment shall be effective upon filing these Articles of
          Amendment in the Department of State.
 
     X    The amendment shall be effective on: October 30, 1992 at 5:00 p.m.
   -----                                       ----------------    ------------
                                                    Date              Hour     
6. (Check one of the following):
 
          The amendment was adopted by the shareholders pursuant to 15
   ------ Pa.C.S. (S)1914(a) and (b).
 
     X    The amendment was adopted by the board of directors pursuant to 15
   ------ Pa.C.S. (S) 1914(c).
 
7. (Check, and if appropriate complete, one of the following):
 
          The amendment adopted by the corporation, set forth in full, is
   ------ as follows:
 
          "5. The aggregate number of shares which the corporation shall be
          authorized to issue is: 10,000,000 shares of Common Stock, par value
          $.3125 per share, aggregate par value $3,125,000."
 
          The amendment adopted by the corporation as set forth in full in
   ------ Exhibit A, attached hereto and made a part hereof.
<PAGE>
 
                                                                   PAGE 13 OF 16
                                   9281-800
 
 DSCB:15-1915 (Rev 89)-2
 
 
 
8. (Check if the amendment restates the Articles):
 
         The restated Articles of Incorporation supersede the original
   ----- Articles and all amendments thereto.
 
 
        IN TESTIMONY WHEREOF, the undersigned corporation has caused these
Articles of Amendment to be signed by a duly authorized officer thereof this
22nd  day of   October ,1992.
- ------       ----------   -- 
 
 
                                          North Pittsburgh Systems, Inc.
                                    -------------------------------------------
                                                (Name of Corporation)
 
 
                                    BY:         /s/ F. D. Reese
                                       ----------------------------------------
                                                     (Signature)
 
                                    TITLE:
                                          -------------------------------------
                                                        President
 
 
                               92 OCT 23 AM 8:56
                               PA DEPT. OF STATE
<PAGE>
 
                                                                   PAGE 14 OF 16
 
 
Microfilm Number  9636-806    Filed with the Department of State on MAY 20 1996
                  --------                                          -----------
 
Entity Number     841529           /s/ Yvette Kane
              ------------    --------------------------------------------------
                                        Secretary of the Commonwealth
 
 
 
              ARTICLES OF AMENDMENT-DOMESTIC BUSINESS CORPORATION
                             DSCB:15-1915 (Rev 90)
 
 
    In compliance with the requirements of 15 Pa.C.S. (S) 1915 (relating to
articles of amendment), the undersigned business corporation, desiring to amend
its Articles, hereby states that:
 
1. The name of the corporation is:      North Pittsburgh Systems, Inc.
                                     -------------------------------------------
 
- --------------------------------------------------------------------------------
 
2. The (a) address of this corporation's current registered office in this
   Comonwealth or (b) name of its commercial registered office provider and the
   county of venue is (the Department is hereby authorized to correct the
   following information to conform to the records of the Department):
 
 (a)    4008 Gibsonia Road       Gibsonia        PA      15044    Allegheny
    ---------------------------------------------------------------------------
    Number and Street            City          State      Zip      County
 
 (b)c/o:    -------------------------------------------------------------------
         Name of Commercial Registered Office Provider             County
 
 
For a corporation represented by a commercial registered office provider, the
county in (b) shall be deemed the county in which the corporation is located for
venue and official publication purposes.
 
3. The statute by or under which it was incorporated is: Business Corporation
                                                         --------------------
   Law, Act of May 5, 1933 (P.L. 364) as amended
   --------------------------------------------------------------------------
             
 
4. The date of its incorporation is:           October 17, 1984
                                     ---------------------------------
 
5. (Check, and if appropriate complete, one of the following):
   
     X
   -----  The amendment shall be effective upon filing these Articles of
          Amendment in the Department of State.
 
          The amendment shall be effective on:                  at           
   -----                                       ----------------    ------------
                                                    Date              Hour     
6. (Check one of the following):
 
     X
   ------ The amendment was adopted by the shareholders (or members) pursuant 
          to 15 Pa.C.S. (S) 1914(a) and (b).
 
   ------ The amendment was adopted by the board of directors pursuant to 15
          Pa.C.S. (S) 1914(c).
 
7. (Check, and if appropriate complete, one of the following):
 
   ------ The amendment adopted by the corporation, set forth in full, is
          as follows:
 
          ----------------------------------------------------------------------
 
          ----------------------------------------------------------------------
 
          ----------------------------------------------------------------------
 
      X   The amendment adopted by the corporation is set forth in full in
   ------ Exhibit A attached hereto and made a part hereof.
 
                                   MAY 20 96
                               PA Dept. of State
 
<PAGE>
 
                                                                   PAGE 15 OF 16
                                   9636-807
 
 DSCB:15-1915 (Rev 90)-2  
 
8. (Check if the amendment restates the Articles):
 
   ------ The restated Articles of Incorporation supersede the
          original Articles and all amendments thereto.
 
 
      IN TESTIMONY WHEREOF, the undersigned corporation has caused these
Articles of Amendment to be signed by a duly authorized officer thereof this
17th day of May, 1996.
- ----        ---  ----
 
 
                                          North Pittsburgh Systems, Inc.
                                    -------------------------------------------
                                                (Name of Corporation)
 
 
                                    BY:         /s/ Gerald A. Gorman
                                       ----------------------------------------
                                                     (Signature)
 
                                    TITLE:            President
                                          -------------------------------------
                                                        
 
<PAGE>
 
                                                                   PAGE 16 OF 16
 
                                   9636-808
 
                                   EXHIBIT A
 
                                        
    "5. The aggregate number of shares which the corporation shall have
authority to issue is:
 
    (a) The Corporation shall have the authority to issue a total of 50,000,000
shares of Capital Stock. Of the 50,000,000 shares of Capital Stock, 40,000,000
shares shall be Common Stock, par value $.15625 per share. The Board of
Directors, at such time or times as it believes appropriate, may divide the
remaining 10,000,000 shares of Capital Stock of the Corporation into one or more
classes of shares of Common Stock, the voting power per share of which shall not
be greater than the voting power per share of the Common Stock issued and
outstanding on April 9, 1996, and/or one or more classes and series of Preferred
Stock, with par or stated value. The determination of the voting rights,
preferences, qualifications, privileges, limitations, restrictions, options,
conversion rights and other special or relative rights of the shares of any such
class or classes of stock shall be accomplished by an amendment to this Article
5 solely by action of the Board of Directors, which shall have the full

authority permitted by law to make such divisions and determinations."